2022+ Suspension MEGA thread - Shock dynos, suspension frequencies, travel, more!

[Racecomp Engineering]

Super big shout out to @trippinbillies40 for sending us a set of OEM dampers early on! Massive help!

This thread is a work in progress and we plan on updating/adding more over time. We still have a lot of work to do...this is an exciting time for us over here at RCE. We are still waiting on our own car () but it's coming soon.

There is some background reading at the end of the post.

Travel:


^Front struts, new vs old


^Front strut overall stroke/travel ~122mm (old was ~149mm) BUT this is not the full story.

Front droop travel appears to be shorter, but it's actually the rebound spring pulling the shaft back in. Overall travel is about the same as 1st gen.

Rears appear to be the same dimensions as previous cars in terms of travel.

Bumpstops are the same as before and 59mm long front, 57mm rear. Again, this is a very bumpstop active car so you’re using the bumpstops over essentially every bump and in every corner. They’re designed that way. Lower the car a lot with lowering springs and you’re compressing the bumpstops before you even sit in the car.


Valving:
Shock dynos! These are BRZ dampers…we do not know for sure yet if the GR86 dampers are identical. I would not trust magazine quotes.





It’s a nice looking curve for a factory Subaru/Toyota damper at this price point and better than what you see in some aftermarket coilovers. It’s not heavily ultra rebound biased which is nice. Actually more compression than rebound til around 2 inches per second.

Good low speed compression, little bit digressive. More front compression than rear.

Rebound has a little progressive to digressive shape to it, which isn’t uncommon. In front, at 2 inches per second you’re at about 85% critically damped with the BRZ springs and 90% with the GR86 springs. Just a little softer in the rear. At higher piston speeds the front never really gets too out of hand (stays above 60% until 8 inches per second) but the rear does go to 50% and lower around 5 inches per second.

All that is to say the shock valving is pretty decent and IMO better than in the past.

And the dampers can support slightly stiffer spring rates. The rear is again a little more sensitive to increased spring rates like last time, so you can’t go too stiff in the rear and expect the dampers to keep up.

Large drops from lowering springs will still cause problems due to available bump travel as on previous cars. In general the previous factory shocks didn’t last super long when ran hard and that will probably still be true, but we’ll see if they’re a little more durable over time.

Springs:
We have not measured spring rates ourselves yet but they are posted elsewhere on the forum:

GR86
2.9 kg/mm front (162 lbs/in)
4.0 kg/mm rear (224 lbs/in)

BRZ
3.1 kg/mm front (174 lbs/in)
3.6 kg/mm rear (202 lbs/in)

This is a little bit firmer overall than the old cars, but not a drastic increase. And remember, the bumpstops are a big part of how these cars handle and those are not included in these rates. Still, the more rearward bias is why the GR86 wants to oversteer a little more than the BRZ.

Motion ratios:
These are the same as before, although I’d like to double check the rear. About 1 (really like 0.97) in the front and 0.76 in the rear. Multiply spring rates by the motion ratio squared to get wheel rates.
*double checking these soon.

EDIT: looking like rear motion ratio is ~0.78

Suspension frequencies:
Using a 55/45 weight split and 3000 lbs with driver, we get roughly:

BRZ – 1.47 Hz front and 1.42 Hz rear.
GR86 – 1.42 Hz front and 1.50 Hz rear.

A slight difference between the 2 cars and overall that’s somewhat soft compared to coilovers. But remember, this doesn’t include those bumpstops. Of course, overall weight and distribution will vary from car to car and driver to driver. You can discuss flat ride amongst yourselves if you like .

Swaybars:
A big part of handling balance is swaybars. This time the sway bars differ from car to car.

The BRZ has an 18.3 mm hollow front bar and a 14mm solid rear bar.
The GR86 has an 18mm solid front bar and a 15mm solid rear bar.

We don’t know what the hollow front bar measures out to, but if someone wants to cut their bar in half for wall thicknesses that would be great. We will eventually have the spring rates of the front bar. Remember swaybars have their own motion ratios too.

The other difference is the new rear swaybar mounting points on the BRZ. We don’t yet know how much of a difference this makes in practice.

Geometry and other things:
Slightly wider rear track.
Slightly longer wheelbase.

Bushings:
Need a little more time here too. The same as before up front at least.

Factory adjustments:
Same as before…meaning nothing but toe adjustment from the factory. Add camber/crash bolts or camber plates to the front and adjustable lower or upper control arms in the rear for camber.

Chassis stiffness:
It's stiffer! More on this soon.

[Racecomp Engineering]

Dump of other notes:
1st gen lowering springs do not work on the 22+ shocks (specifically the rear spring).

You can probably swap complete 1st gen damper/spring/tops assemblies with 2nd gen and vice versa (untested).

We are developing new springs for the new car.

Coilovers are more straightforward and will swap without issue at least in terms of fitment.

The rear upper shock mount is different...appears to be harder rubber but not sure. SHOULD swap over fine, unclear if there is a stack height difference.

All new RCE parts are being developed for new and old cars concurrently (except springs as mentioned).

Thread on 1st vs 2nd gen parts compatibility
https://www.ft86club.com/forums/showthread.php?t=147698

Tech background stuff
Basics on motion ratios:
https://www.instagram.com/p/B3cDzqOD..._web_copy_link

Basics on suspension frequencies:
https://www.instagram.com/p/B6TKG6Un..._web_copy_link

Basics on shock dynos:
https://www.instagram.com/p/CJd5GH4H..._web_copy_link

[marco_mc22]

The reduced droop travel disappointed me….it’s still a strut though.

[Turdinator]

Originally Posted by Racecomp Engineering

...Bumpstops are the same as before and 59mm long front, 57mm rear. Again, this is a very bumpstop active car so you’re using the bumpstops over essentially every bump and in every corner. They’re designed that way. Lower the car a lot with lowering springs and you’re compressing the bumpstops before you even sit in the car...


...This is a little bit firmer overall than the old cars, but not a drastic increase. And remember, the bumpstops are a big part of how these cars handle and those are not included in these rates. Still, the more rearward bias is why the GR86 wants to oversteer a little more than the BRZ...


...A slight difference between the 2 cars and overall that’s somewhat soft. But remember, this doesn’t include those bumpstops. Of course, overall weight and distribution will vary from car to car and driver to driver. You can discuss flat ride amongst yourselves if you like .

If bumps stops play such a large part in the stock suspension setups of both the old and new car why is no one offering different bumpstops to improve handling or comfort? Are they just not sexy enough from a marketing point of view? It seems like it would be a good OEM+ kind of mod.

[strat61caster]

Originally Posted by Turdinator

If bumps stops play such a large part in the stock suspension setups of both the old and new car why is no one offering different bumpstops to improve handling or comfort? Are they just not sexy enough from a marketing point of view? It seems like it would be a good OEM+ kind of mod.

No money to be made, many options on the shelf for those that want to, easily cut 'em to length or add spacers to modify what you're looking for for way cheaper then springs.

Eibach and kw and ST give them to you for free when you buy their springs/coilovers. Googling now I saw some OEM rubbers for <$5.


https://www.summitracing.com/parts/e...xoC8pIQAvD_BwE

https://shop.penskeshocks.com/product/bump-rubber/

https://www.speedwaymotors.com/Speed...oft,59316.html

https://www.fcpeuro.com/products/aud...RoCxM0QAvD_BwE

[Turdinator]

Originally Posted by strat61caster

No money to be made, many options on the shelf for those that want to, easily cut 'em to length or add spacers to modify what you're looking for for way cheaper then springs.

Eibach and kw and ST give them to you for free when you buy their springs/coilovers. Googling now I saw some OEM rubbers for <$5.


https://www.summitracing.com/parts/e...xoC8pIQAvD_BwE

https://shop.penskeshocks.com/product/bump-rubber/

https://www.speedwaymotors.com/Speed...oft,59316.html

https://www.fcpeuro.com/products/aud...RoCxM0QAvD_BwE

I know what you're saying but what lengths and rates improve my handling? I'd rather pay for the experience and time of professionals to find the right combination. I mean I could pay for custom springs if i want but I'd rather buy springs from Racecomp as they have put in the time and effort to come up with a length and rate that works.

[DocWalt]

I wonder if the reduced droop travel is due to the rebound spring in the front shocks. Can you extend it further by pulling on it?

[Racecomp Engineering]

Originally Posted by DocWalt

I wonder if the reduced droop travel is due to the rebound spring in the front shocks. Can you extend it further by pulling on it?

This is correct!

- Andrew

[ayoshioka1]

Excited to see further development from you guys. i will be waiting for the new coilovers for my GR86 when time comes. both SS1 on my old BRZ and STi has been flawless.

[treedodger]

On my GR86 Struts, there appears to be a rebound spring, because when I pull on it, it extends another 1/2in or so.

Originally Posted by DocWalt

I wonder if the reduced droop travel is due to the rebound spring in the front shocks. Can you extend it further by pulling on it?

[DocWalt]

Originally Posted by treedodger

On my GR86 Struts, there appears to be a rebound spring, because when I pull on it, it extends another 1/2in or so.

Interesting. Wonder if they're really that different than the BRZ. Thanks!

[Racecomp Engineering]

Originally Posted by treedodger

On my GR86 Struts, there appears to be a rebound spring, because when I pull on it, it extends another 1/2in or so.

Originally Posted by DocWalt

Interesting. Wonder if they're really that different than the BRZ. Thanks!

I think they're the same and I think Myles just needs to pull harder.

I'll have a look again...we used that first set for something special but I do have another set to play with now too.

- Andrew

[Racecomp Engineering]

Random update that may interest someone...

In between testing some 3 way coilovers and other fun stuff, I've put the 2022 BRZ dampers and springs on my 2016 BRZ. Just for kicks. The car is otherwise now almost completely stock suspension wise (boooring) with the exception of OEM crash bolts, my bling STI strut bar, and rear Whiteline subframe + diff bushing inserts.

The ride quality is very good, better than OEM 2016 dampers by a significant margin. It's downright comfortable. This is on really awful Baltimore city roads and long trips to the mountains. It's likely better than 2017-2020 dampers too. Better than Bilstein B6, Koni, etc. Almost like a normal car.

Which...I do not love in terms of handling and feel. It's a little sloppy and not very confidence inspiring, especially the rear. This isn't just me going from those 3 ways to an OEM suspension. I would still prefer the 22 dampers to any of the 1st gen OEM dampers and a lightly used set of these would be a good choice for someone looking for more comfort.

Just some quick thoughts.

- Andrew

[Racecomp Engineering]

Also, posted this elsewhere on the rear swaybar mounting method for BRZ...reposting here:

Originally Posted by Racecomp Engineering

The swaybars themselves?

The 2022 GR86 uses the 2017-2020 set up, 18mm front and 15mm rear.
The 2022 BRZ uses a new 18.3mm hollow front bar and a 14mm rear.

The equations for figuring out spring rate from swaybar dimensions aren't too hard and there are numbers posted on this forum somewhere. Have to remember the motion ratio for the swaybars as well (which can be different than the main spring motion ratios).

That new hollow BRZ front bar has been quoted as a mild 2.3% stiffer than the standard 18mm solid front bar. That's not very much but it is probably a little lighter which is nice. As with the aluminum front hubs you can see Subaru made effort (at extra cost) to reduce unsprung weight. Which is good.

With both springs and swaybars you have more front roll resistance and less rear roll resistance with the BRZ vs the GR86.

The rear swaybar mounting method is a related but different question. Like others said the new BRZ takes the subframe and subframe bushings out of the equation, meaning it acts without compliance from the subframe bushings. The subframe on standard bushings moves more than you think. Yes you can add subframe bushing inserts but something like a solid bushing insert or full replacement adds noise and is not great on a daily driver.

Does that make the 14mm BRZ rear act like a stiffer rear bar? Not really, but it's a more linear and direct action. Which is good IMO.

All the discussion about the playful nature of the GR86 vs the stability of a BRZ is largely the spring and swaybar rates, not the front hubs or rear swaybar mounts.

This is just my opinion but the GR86 using the old style front hubs and the rear swaybar mounts was simply cost savings. Arguably the solid vs hollow front bar too (2.3% difference in stiffness isn't much).

So why is the GR86 sometimes faster around a track? Well the new BRZ components are better but not a huge change. Meanwhile, off the factory floor these cars desperately need more front camber. Without that, more rear roll stiffness from the GR86 helps a lot to get the car to turn.

With the aluminum front hubs and new rear swaybar mount, the GR86 would be largely similar and still have the "playful" character.

The best handling 2022 would be a BRZ with GR86 rear springs and the OEM crash bolts for a tiny bit more camber. Maybe the GR86 rear 15mm bar too.

- Andrew